| In order to confirm the physiological and biochemical characteristics of carbendazim-resistant isolate ZY-D and tebuconazole-resistant isolate ZY-W of Fusarium oxysporum f. sp. fragariae, and calculate the resistance risk and mechanism, comparison was conduced between ZY-D with53.9folds’carbendazim-resistance, ZY-W with34.2folds’ tebuconazole-resistance and ZY on the activity of phenylalanine ammonia lyase (PAL) and peroxidase (POD), the sensitivity to osmolarity, the relative leakage, and the contents of solution protein. The results were as follows:1. The defense enzyme activities tested with UV spectrophotometer showed that:Under different condition, the PAL and POD activities of ZY-D and ZY-W were always higher than that of ZY, and the activities of three isolates increased with the concentration of treated fungicide, with every fungicide treatment higher than the control. The POD activities of three isolates increased with the treatment time, and reached the peak at24h; the PAL activities of ZY-D and ZY-W increased at first and the decreased, and ZY-D arrived at the top at6h, while ZY-W reached at1.5h; the PAL activity of ZY was always rising.2. The osmolarity sensitivity tested by mycelia growth rate showed that, three isolates were sensitive to high osmolarity (8%), with ZY-W sensitive to mid-high osmolarity (6%and8%). Low concentration of NaCl (20g/L) could increase the growth of ZY, while high concentration restraining the growth. The mycelia growth of ZY-D and ZY-W had negative relationship with NaC1concentration, with ZY-W more notable.3. The membrane permeability tested by conductivity showed that, the relative leakage of ZY-W was always lower than ZY, after treated by different concentration of tebuconazole and different time, which means that ZY-W could regulate osmolarity better than ZY. However, the other resistant isolate ZY-D always leakaged more electrolyte than ZY.4. The solution protein contents of three isolates were sequenced as follows:ZY-W> ZY-D> ZY. The soluble protein contents of ZY-W and ZY-D were0.34and0.19folds higher than ZY, respectively. Significant differences can be found among three isolates (P<0.05).5. In the electrophoretic patterns of esterases, one characteristic band with R_f value0.24was found in ZY-W. |
